Research On Scalable Multimedia Signal Coding Transmission Methods

Scalable image and video coding is an attractive and promising technique in modern multimedia communication system, it can accommodate to different bandwidth and diversity of devices presenting different needs in terms of quality, resolution and frame rate. But, scalable bitstream is very sensitive to channel error because that the data error or loss in the scalable stream will impact the decoding of the subsequent stream seriously. Therefor, the improvement of the robustness of scalable encoded stream in error-prone channel becomes a research focus.Based on the study on present foreign and domestic research, this dissertation focuses on the research for transmission of scalable image and video stream over error channel. The main contributions of this dissertation include the three parts as followed:(1) A JSCC scheme is proposed for transmission of wavelet-based scalable image stream over packet erasure channel. Layered Multiple Description Coding (LMDC) is adopted to encode the image into several independent sub-streams to improve error resilience, and RS Code is adopted to combat the packet erasure. By reordering the source coding symbols and RS coding symbols through the designed sort method, separate stream is placing into separate channel packet to maintain independence. The decoder adopts the same sorting algorithm as encoder to obtain the sorting information of souce and channel coding symbols. Experimental results show that the proposed scheme is lees affected by balance of substreams and improves the received image quality with less overhead.(2) A JSCC scheme based on Unequal Error Protection (UEP) Fountain Code is proposed for transmission of scalable video stream over packet erasure channel. Firstly, a novel encoding scheme for regular variable-node degree LT Codes is proposed. Comapred with the existing scheme, the proposed scheme reduces the complexity; meanwhile, the waterfall area (avalanche area) in decoding is improved by modifying the degree distribution. Secondly, on this basis, one UEP scheme is proposed. Finally, the proposed UEP methods are used to protect transmission of H.264/SVC scalable video stream in unicast and multicast channel. Simulation results show that the proposed method can improve system performance, and reduce the encoding complexity.(3) A cross layer JSCC multicast scheme is proposed for transmission of scalable video stream over wireless broadcast channel. Layered video coding and Adaptive Modulation and Coding (AMC) are combined and the impact of layered structure to system performance is considered in this scheme. Firstly, the system utility is maximized by allocating different resources inter-and intra-multicast groups optimally. Then, the layered video coding structure is modified according to resource allocation, so that the layered structure is compatible with available system resources and the channel conditions of different users. Simulation results show that this scheme takes full advantage of radio resources, and improves the system performance.